Co-polymers of long chain alkyl acrylates with N-containing olefins and their use as flow improvers for crude oils

ABSTRACT

Copolymers of long-chain alkyl acrylates or methacrylates of the formula 
     
         CH.sub.2 ═CR.sup.1 --CO--OR.sup.2                      (I) 
    
     in which R 1  is a hydrogen atom or a methyl group and OR 2  is a fatty alcohol radical with 16 to 34 carbon atoms and nitrogen-containing olefins can be used as flow improvers for crude oils.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to copolymers of long-chain alkyl acrylates withN-containing olefins, the process for their production and their use asflow improvers for crude oils.

2. Description of the Related Art

Depending on their respective origin, crude oils can containconsiderable amounts of paraffins. When cooled below a certaintemperature (cloud point) the paraffin gradually crystallizes out of theoil and forms a three-dimensional network of scales and/or needles whichis filled with oil. Such a structure gives the crude oil disadvantageousproperties with respect to flowability and ease of handling.

The effect of the paraffin crystallizing out in the crude oil is thatthe oil scarcely or no longer flows, it can no longer be pumped or onlywith a great expenditure of energy and forms deposits in the pipelines,storage containers and ships tanks, which lead to considerable losses inproduction and capacity.

Crude oils found in oil-bearing layers have a temperature which variesaccording to depth. In the deeper layers from which the oil isextracted, higher temperatures prevail at which the paraffin is stillfluid and dissolved in the oil. If crystallisation inhibitors are addedto a crude oil containing paraffin in this state, the effect is on theone hand to lower the solidification point, and on the other hand toalter the crystal structure of the separated paraffin with improvementof the flow properties of the crude oil.

As a measure of the effect of a flow improver the solidification pointor the lowering of the solidification point in comparison to the crudeoil without flow improvers is given in °C. It is in this sense possibleto speak of pour-point depressants, PPDs, as well as flow improvers.

In the prior art a number of compounds with a crystallisation inhibitingeffect are described, see DE-OS 2,926,474, 3,237,308, 3,226,252,2,210,431; EP-OS 61, 894; U.S. Pat. Nos. 4,663,491, 4,284,414,3,957,659, 3,854,893. Usually these are co-polymers of C₁₆ C₂₄methacrylates with short chain methacrylates, aminoalkylmethacrylates aswell as various olefins with or without polar groups. The C₁₆ C₂₄-alcohols characteristically represent the usual cuts of the productfrom untreated or petrochemical raw materials.

A special position is held by a commercial product, which is used forcomparison purposes in the following and is therefore described as a"comparative product" and can be used in many different crude oils as aflow improver. The exact structure of this product is not known,presumably it is one of the co-polymers described in U.S. Pat. Nos.3,957,659 and 3,868,231 of

(a) a C₁₆ C₂₄ -acrylate and (b) 4-vinylpyridine.

The two comonomers have very different copolymerization parameters(acrylic acid octyl ester:v₁ approximately 0.1: 4-vinylpyridine:v₂approximately 1.6). They are therefore difficult to co-polymerize andrequire special measures (e.g. a programmed "Monomer AdditionProcedure") in the products.

DESCRIPTION OF THE INVENTION

Other than in the operating examples, or where otherwise indicated, allnumbers expressing quantities of ingredients or reaction conditions usedherein are to be understood as modified in all instances by the term"about".

The present invention relates to co-polymers of long-chain alkylacrylates with N-containing olefins, which because of the acrylatestructure present in both monomers are distinctly easier to co-polymerize and are particularly suitable as flow improvers for crudeoils. The copolymers of the present invention are comprised of units of:(1) an acrylate of the formula I

    CH.sub.2 ═CR.sup.1 --CO--OR.sup.2                      (I)

wherein R¹ is hydrogen or methyl, and R² is a linear or branched,saturated or unsaturated aliphatic radical having from 16 to 34 carbonatoms, and (2) N containing olefins selected from the group consistingof (A) a compound of the formula II

    R.sup.3 --R.sup.4 --O--CO--CR.sup.5 ═CH.sub.2          (II)

wherein R³ is a cyclic imide having of the formula III or IV ##STR1##wherein R⁵ is hydrogen or methyl, R⁶ and R⁷ are together or separatelyhydrogen or C₁ -C₄ -alkyl groups or when taken together are ringfragments of an unsubstituted or a C₁ -C₄ alkyl substituted ring have 5or 6 carbon atoms, R⁴ is (a) a straight-chain or branched alkylene grouphaving 1 to 12 carbon atoms optionally subsituted with --OH or NH₂group, (b) a straight-chain or branched alkylene group having 1 to 12carbon atoms containing the --CH₂ --CH₂ --O--CH₂ --CH₂ -- or --CH₂ --CH₂--NH--CH₂ --CH₂ -- moiety when the alkylene group contains at least 4carbon atoms, (c) a cyclic C₅ - or C₆ - alkylene group or (d) a C₁ -C₄-alkylene- substituted phenylene group, (B) a compound of formula V

    R.sup.3 --R.sup.8 --CO--OR.sup.9 --O--CO--CR.sup.10 ═CH.sub.2 (V)

wherein R³ is a cyclic imide having of the formula III or IV ##STR2##wherein R⁶ and R⁷ are together or separately hydrogen or C₁ -C₄ alkylgroups or when taken together are ring fragments of an unsubstituted ora C₁ -C₄ alkyl substituted ring having 5 or 6 carbon atoms, R⁹ is C₂-C₁₀ alkylene group, R¹⁰ is hydrogen or methyl, R⁸ is a phenyleneradical or an alkylene group of the formula ##STR3## wherein R²⁰ is ahydrogen atom or a branched alkyl radical having from 1 to 11carbonatoms, and R⁹ is a C₂ -C₁₀ -alkylene group, (C) a compound of formula VI##STR4## wherein R¹⁶ is hydrogen or methyl, .R¹² is a phenyl or benzylgroup, R¹³ is a C₁ -C₁₆ -alkyl group and R¹⁴ is a C₂ -C₆ -alkylenegroup, (D) a compound of formula VII

    R.sup.17 --CO--NH--R.sup.18 --O--CO--CR.sup.19 ═CH.sub.2 (VII)

wherein R¹⁹ is hydrogen or methyl, R¹⁷ C₇ -C₃₃ -alkyl group, R¹⁸ is a C₂-C₄ -alkylene group or combinations thereof in molar ratios of I, to II,V, VI or VII of from about 1:0.1 to about 1:10.

Individual olefins of formula II, V, VI, VII or also mixtures of theseolefins can be used in the co-polymerization.

The acrylates of formula I represent fatty acid esters of acrylic andmethacrylic acids; the derivatives of acrylic acid are preferred. Thealcohol component of the acrylates of formula I is formed by alcoholswith 16 to 34 carbon atoms, in particular cetyl-, stearyl-, arachidyl-,behenyl- and lignoceryl-alcohol, in which special industrial C₁₈ /C₂₂fatty alcohol mixtures with behenyl alcohol contents of above 40% toabove 70% are particularly preferred.

In the acrylates of formula II, R¹, defined as above, is preferablyhydrogen. The groups R⁶ and R⁷ can be hydrogen or C₁ -C₄ -alkyl groupssuch as methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl and t-butyl;they can also form a C₅ or C₆ ring such as cyclopentane, cyclopentene,benzene, 1,4-dihydrobenzene, cyclohexene, or such a ring substitutedwith the C₁ -C₄ -alkyl group. The group of N-containing olefinsaccording to formula II, as well as the group of formula V is preferablyselected from the group formed by the radicals of phthalimide,tetrahydro-phthalimide, methyl-tetrahydro- phthalimide, maleinimide andsuccinimide; special examples of phthalic acid derivatives, in additionto phthalimide and hexahydro-phthalimide, are1,2,3,6-tetrahydro-phthalimide, 4-methyl-1, 2,3,6-tetrahydro-phthalimide and 4-methylhexahydro-phthalimide.

The group R⁴ in the formula II represents a straight-chain or branchedalkylene group with 1 to 12, and in particular 1 to 6, carbon atoms, inparticular ethylene, propylene, butylene, pentylene, hexylene, octylene,decylene and dodecylene; the aforementioned alkylene groups with 1 to 6carbon atoms are preferred. The group R⁴ can also be phenylene or C₁ -C₄-alkylene-substituted phenylene, in particular methylene-phenylene. TheN-acrylates of formula II are preferably obtained when the correspondingcyclic anhydrides of the formula ##STR5## are reacted with aminoalcoholsof the formula

    H.sub.2 N--R.sup.5 --OH

particular with amino-ethanol, omega-amino-propanol, -butanol, pentanol,-hexanol, -octanol, -decanol, -dodecanol, 1-amino-2-propanol,4-hydroxyethyl- or 4-hydroxymethyl-aniline, 4-aminocyclohexanol. Thereaction then takes place of the free OH-groups of the compounds thusobtained with acrylic or methacrylic acids or with reactive derivativesof these by the usual methods.

Other aminoalcohols can be used in this reaction e.g. 1-amino-2-hydroxypropane, 2-amino-1-hydroxypropane, 2-amino-2'-hydroxy-diethylether, 2-amino-2'-hydroxy-diethylamine and2-amino-1-hydroxybutane as well as1-amino-2,2-dimethyl-3-hydroxypropane.

Another preparation process for N-containing olefins of the generalformula II, involves starting with the appropriate N-unsubstitutedcyclic imides and reacting these with formaldehyde; the N-hydroxymethylcompounds obtained can then be esterified in the usual manner withreactive derivatives of acrylic and methacrylic acids.

In the N-containing olefins of formula V, in which R¹⁰ is hydrogen ormethyl, R³ is a cyclic imide radical are defined as above, the R⁸ groupmeans a phenylene radical or an alkylene group with 1 to 12 carbonatoms, with the proviso that the alkylene radical has the structure##STR6## where R²⁰ is a hydrogen atom or a possibly branched alkylradical with 1 to 11 carbon atoms. Compounds in which the radical R⁸ isa methylene group or a C₁ -C₅ mono-alkyl-substituted methylene group arepreferred here. The meanings for the C₁ -C₅ -alkyl substituents are thesame as given above for C₁ -C₄, but including pentyl.

N-containing olefins of formula V can be obtained by reacting theappropriate cyclic anhydrides initially with amino acids of the generalformula

    H.sub.2 N--R.sup.8 --COOH

Suitable amino acids are glycine, alanine, valine, leucine, isoleucine,phenylalanine, caprolactam and the like, and glycine is preferred.Another suitable amino acid is 4-amino benzoic acid. The imidocarboxylicacids thus obtained can then be reacted in the usual manner withhydroxy-C₂ -C₁₀ -alkyl-acrylates and -methacrylates, in particular C₂-C₄ -alkyl acrylates, and -methacrylates; particularly preferred here isthe reaction with the hydroxyethyl derivatives of the aforementionedacrylic acids.

In the N-containing olefins of formula VI, R¹² is a phenyl or benzylgroup, R¹³ is a C₁ -C₁₆ -alkyl group, preferably a C₁ -C₄ -alkyl group,and R¹⁴ is a C₂ -C₆ -alkyl group, preferably a C₂ -C₄ -alkyl group.Alternatively, R¹² and R¹³ could also be C₁ -C₁₆ -alkyl groups,preferably C₁ -C₄ -alkyl groups with the above meanings R¹⁴ could be aphenylene group.

N-containing olefins of formula VI can be obtained, by reactinghydroxyalkyl amines of the formula

    R.sup.12 R.sup.13 N--R.sup.14 --OH

with acrylic or methacrylic acids or esters or reactive derivatives ofthe acids in the usual manner. As particularly advantageous hydroxyalkylamines those are used, in which R¹² is a phenyl or benzyl group, R¹³ isa C₁ -C₄ -alkyl group and the hydroxyalkyl group has 2 to 4 carbonatoms; alternatively R¹² and R¹³ can be C₁ -C₄ -alkyl groups, where ahydroxyphenyl group takes the place of the hydroxyalkyl group.Particularly preferred representatives of the N-containing olefins offormula VI are those in which R¹² is benzyl or phenyl, R¹³ is methyl orethyl and R¹⁴ is an alkylene radical with 2 to 6 carbon atoms. They areobtained starting from the following hydroxy alkyl amines:

N-benzyl-N-methyl-hydroxy-ethylamine, -propylamine, -butylamine,-pentylamine, -hexylamine, as well as the corresponding N-benzyl-N-ethyl-, N-phenyl-N-methyl- and N-phenyl-N-ethyl-N-hydroxy alkylamine.

In the N-containing olefins of formula VII, R¹⁷ is a C₇ -C₃₃ -alkylgroup, in particular a C₁₅ -C₂₃ -alkyl group. The radical R¹⁷ -CO istherefore the radical of a C₈ -C₃₄ -, in particular of a C₁₆ -C₂₄ -fattyacid or an industrial mixture of these from natural, e.g. of vegetable,animal or marine animal or synthetic origin. Typical examples of thesefatty acids are caprylic, caprinic, lauric, myristic, palmitic, stearic,arachic, behenic, and montanic acid, and also lauroleic, myristoleic,palmitoleic, oleic and erucic acid. The N-containing olefins of theformula VII can be obtained by the reaction of the corresponding fattyacids or fatty acid mixtures with C₂ -C₄ -alkanolamines to thecorresponding fatty alkanol amides and the acylation of the hydroxylfunction in the usual manner with reactive derivatives of acrylic ormethacrylic acid.

The reaction of acrylates of formula I with N-containing olefins II, V,VI and VII takes place in the presence of inert organic solvents such asxylene, tetraline and other solvents with higher boiling points, e.g.solvents high in aromatic substances, such as Solvesso 200, and in thepresence of radical polymerization initiators, which are usual for theco-polymerization of acrylates, cf. Kirk-Othmer, Volume 13, 1981, pp 355to 373; a preferred initiator is for example azo-isobutyro-dinitrile(AIBN). The co-polymerization usually takes place at temperatures ofapproximately 80° to 100° C.

Co-polymers of the type mentioned in the introduction have also provedparticularly advantageous, which by the co-polymerization of acrylatesof formula I

    CH.sub.2 ═CH--CO--OR.sup.2                             (I)

in which OR² is a fatty alcohol radical with 16 to 24 carbon atoms, inparticular an industrial fatty alcohol mixture which is high in behenylalcohol (content of behenyl alcohol of more than 40 to more than 70%),with an N-containing olefin of formula II in which R³ is defined asabove and R⁴ is an alkylene radical with 2 to 8, and in particular 2 to3 carbon atoms, in molar ratios of the compounds VI to II of from about1:0.5 to about 1:2. Copolymers of the type mentioned in the introductionhave proved particularly advantageous, which by the copolymerization ofan acrylate of formula I, in which the group OR² is a fatty alcoholradical with 16 to 24 carbon atoms, in particular an industrial fattyalcohol mixture which is high in behenyl alcohol (behenyl alcoholcontent of more than 40 to more than 70%), with an N-containing olefinof formula VI in which R¹³ is a C₁ -C₄ -alkyl group and R¹⁴ is anethylene group, in molar ratios of the compounds I to VI of from about1:0.1 to about 1:0.5.

Furthermore the invention relates to a process for preparation ofcopolymers of the type mentioned in the introduction, as well as theiruse as flow improvers for paraffin-rich crude oils. In using thecopolymers as flow improvers for paraffin-rich crude oil, the copolymerscan be dissolved directly in the crude oil or can first be dissolved inan aromatic hydrocarbon solvent such as toluene or xylene and theresulting solution dissolved in the crude oil to faciliatate theirinclusion in the crude oil. The quantity of coplymers dissolved in thecrude oil varies with the particular type of crude oil. The copolymersare usually incorporated into crude oil at a level of from about 100 ppmto about 3000. The preferred amount is from about 150to about 2000 ppm.

The N-containing olefins used to prepare the copolymers of the presentinvention are prepared by the following processes.

1. Preparation of N-containing olefins of the general formulae II, V,VI, and VII (starting compounds for the copolymerization=N-containingolefins A to M).

In the following table 1 the prepared N-containing olefins, A to H aresummarized with their starting compounds and their physicalcharacteristics. They are obtained starting from the correspondinganhydrides in a two-stage synthesis using the hydroxyimides according tothe following general method:

(a) Hydroxyimide Synthesis

1 mole of the amino alcohol is slowly added in drops to 1 mole of theappropriate anhydride in 400 ml xylene, during which the mixture heatsup. After the addition is completed it is heated to 170° C. and thereaction water is distilled off azeotropically to the water separator.After approximately 3 hours the dehydration is complete. The product canbe isolated by removal of the solvent or further reacted directly insolution.

                                      TABLE 1                                     __________________________________________________________________________    Olefins containing N from anhydrides, amino alcohols and acrylic acids.                                                   Reaction with acrylic acid                  Hydroxyimide-Synthesis                                                                    Yield.sup.1                                                                       m.p.              Yield                                                                             m.p.                          Anhydride Amino alcohol                                                                             %   °C.                                                                       OHZ.sup.2                                                                         Product    %   °C.                                                                        N-olefin                  __________________________________________________________________________    phtalic acid                                                                            2-aminoethanol                                                                            98  127                                                                              --  (phthalimido-N-                                                                          92  105 A                         anhydride                        ethyl)-acrylate                              Tetrahydrophthalic                                                                      "           100 70 --  (tetrahydrophthal-                                                                       89  liquid                                                                            B                         acid anhydride                   imido-(N-ethyl)-                                                              acrylate                                     4-methylhexahydro-                                                                      "           98  -- 259 (4-methylhexahydro-                                                                      91  liquid                                                                            C                         phthalic acid                    phthalimido-N-ethyl)                         anhydride                        acrylate                                     Succinic acid                                                                           "           97  60     (Succimido-N-                                                                            50      D                         anhydride                        ethyl)-acrylate                              phthalic acid                                                                           1-aminopropanol-2                                                                         97  88     (phthalimido-N-iso-                                                                      85   65 E                         anhydride                        propyl)-acrylate                             phthalic acid                                                                           2-(4-aminophenyl)-                                                                        94     201 [phthalimido-N-                                                                          89  105 F                         anhydride ethanol                (4-ethyl-phenyl)]                            4-Methylhexa-                                                                           6-aminohexanol-(1)                                                                        100      201.5                                                                           (4-methylhexahydro-                                                                      90  liquid                                                                            G                         hydro-phthalic acid              phthalimido-N-hexyl)-                        anhydride                                                                     acrylate                                                                      succinic acid                                                                           "           96     252 (Succinimido-N-                                                                          74      H                         anhydride                        hexyl)-acrylate                              __________________________________________________________________________     .sup.1 calculated by the water collected                                      .sup.2 OHZ  hydroxy number in mg KOH/g substance                         

(b) Reaction of the hydroxyimides obtained above with acrylic acid tothe N-containing olefins, A to H.

1 mole of the respective hydroxyimide is heated with 1 mole of acrylicacid in 200 ml of xylene with the addition of 1 g of hydroquinonemonomethylether and 1 g of concentrated sulfuric acid in the waterseparator to approximately 140 to 150° C., until approximately thetheoretical amount of water is removed. The product can be used directlyfor polymerization or can be isolated after washing with water andbicarbonate solution and removal of the xylene.

2. Preparation of further N-containing olefins. I, J, K, L, and M.

(Phthalimido-N-methyl)acrylate (I).

100 g phthalimide (0.68 mole) is added to 88 ml of 37% formaldehydesolution and 190 ml of distilled water and stirred for 4 hours at 98° C.The slightly cloudy solution is filtered while hot. During cooling theintermediate product, (N-hydroxymethyl)-phthalimide is precipitated as awhite, crystalline solid. m.p. 104° C.

For the preparation of the title compound, 1 mole of (N-hydroxymethyl)-phthalimide and 1 mole of acrylic acid are put in 600 ml of xylene andafter the addition of 1 g of hydroquinone monomethylether and 1 g ofconcentrated sulfuric acid it is esterified at approximately 140° C.until no more reaction water is formed. The remaining product after theremoval of the solvent has a m.p. of 115° C.

Phthalimido-N-(methylcarboxyethyl)-acrylate (J).

N-(phthaloylglycine):

1 mole of phthalic acid anhydride, 1 mole of glycine and 0.1 mole oftriethylamine are heated in the water separator in 200 ml of toluene toapproximately 110° to 130° C. Thereby over 3 hours approximately 95% ofthe theoretical water quantity is separated. The solvent is removed at amaximum of 140° C. in a vacuum. The solid residue is triturated in 300mlof 0.5 n HCl, suction-filtered, washed several times with water anddried. A white product is obtained, m.p. 190° C.

Conversion of N-phthaloylglycine to N-containing olefin J.

41.0 g (0.2 mole) N-phthaloylglycine and 69.9 g (0.6 mole) ofhydroxyethyl acrylate are heated in 200 ml of toluene with the additionof 0.6 g hydroquinone monomethylether and 0.6 g of concentrated sulfuricacid in the water separator; the internal temperature amounts to 110° to130° C. After 3.5 g of water has been separated, (theoretical value 3.6g) which corresponds to a conversion of approximately 97%, the reactionis interrupted (after approximately 3.5 hours). After diluting with afurther 200 ml of toluene the excess hydroxyethyl acrylate is removed bywashing with water. The reaction mixture is then neutralized withbicarbonate and the solvent removed, whereby the product precipitates asa yellow oil (OH-number 0, residual acid number=8 (each mg KOH/gsubstance).

Phthalimido-N-(methylcarboxypropyl)-methacrylate (K).

1 mole of phthaloylglycine and 1 mole of hydroxypropyl-methacrylate areheated in 400 ml of toluene after the addition of 1 g of hydroquinonemonomethylether and 1 g of concentrated sulfuric acid in a waterseparator, until approximately the theoretical quantity of water isseparated. The toluene solution is washed with water and the toluene isdrawn off by a vacuum.

C_(16/18) -fatty acid amido-ethylacrylate (L).

C_(16/18) a-fatty acid monoethanolamide.

0.5 mole of C_(16/18) -fatty acid methyl ester and 1 mole of 2-(methylamino)-ethanol are mixed, 1% powdered tin is added and the mixture isheated for 6 hours at 150° C. Thereby approximately 80% of thetheoretical methanol quantity is separated. Then the bath temperature isincreased to 200° C. and placed under a vacuum for 30 minutes, to removethe remaining methanol as well as the excess aminoalcohol. A productwith a melting point of 40° C. is obtained.

C_(16/18) -fatty acid amidoethyl acrylate:

1 mole of acrylic acid and 1 mole of the previously prepared C_(16/18)fatty acid monoethanolamide together with 1 g of hydroquinonemonomethylether and 1 g of concentrated sulfuric acid are placed in 300ml of toluene and esterified for approximately 12 hours at 140° C. Thenthe solution is filtered and the toluene is extracted by a vacuum. Theproduct obtained has a residual OH number of 15 and a residual acidnumber of 11.

Preparation of N-benzyl-N-methylaminoethylacrylate (M).

247.9 g (1.5 mole) of N-benzyl-N-methylethanolamine (commercial product)and 126.0 g (1.75 mole) of acrylic acid are heated in a water separatorin 300 ml of xylene with the addition of 1.5 g of hydroquinonemonomethylether and 1.5 g of concentrated sulfuric acid. After 6 hours27 g of the water has been separated, which corresponds to aquantitative reaction. Towards the end of the reaction the internaltemperature is increased to 170° C. by the removal of xylene. After theusual finishing processes a yellow-brown, highly fluid oil with anOH-number of 6.5 and an acid number of 9 mg KOH/g resulted.

3. Preparation of the copolymers of the invention.

The preparation of the copolymers of the invention are summarized in thefollowing tables 2 to 9. Furthermore, in the column "Pour-Point", thesetables contain the pour- points of a crude oil mixture which can beobtained by adding 400 ppm. of the copolymers of the invention, andwhich has a pour-point of +21° C. without any flow-improving additives.

EXAMPLE 1

Copolymers from (phthalimido-N-ethyl)acrylate (olefin A containing N)and behenylacrylate (approx. 70% C₂₂ -content).

24.5 g (0.1 mole) of (phthalimido-N-ethyl)acrylate and 37.5 g (0.1 mole)of behenylacrylate are heated to 80° C. in 37.5 g of xylene. Then withinone hour 0.46 g (2.8×10⁻³ mole) of azo-bis-isobutyronitrile AIBN) areadded in 24.5 g of xylene. There is then a post-reaction time of 2 hoursat 100° C.

EXAMPLES 2 to 20, 27, to 41, 44, 47, 50, 52

The preparation of these copolymers is carried out according to themethod given in Example 1. The method is the Batch Method referred to inTables 2-9.

EXAMPLES 21 to 26, 42, 43, 45, 46, 51 and 53

The preparation of the copolymers of the invention according to theseexamples is explained in the following using Example 24. This method isreferred to as the Monomer Addition Procedure in Tables 2-9.

Preparation of(phthalimido-N-ethyl)-acrylate-behenylacrylate-polymers(by the monomeraddition procedure).

A solution of 2.45 g (0.01 mole) (phthalimido-N-ethyl)-acrylate and 3.75g (0.01 mole) of behenyl acrylate in 3.75 g of xylene (=10% of themonomer mixture) is added within 6 minutes at 80° C. to 0.046 AIBN in2.45 g xylene (=10% of the starter solution). Within 54 minutes at thesame temperature a 80° C., hot solution of 22.5 g (0.09 mole)(phthalimido-N-ethyl)-acrylate and 33.75 g (0.09 mole) behenylacrylatein 33.75 g of xylene and a solution of 0.414 g AIBN in 22.05 g xyleneare added simultaneously. There was then a post-reaction period of 2hours at 100° C.

The preparation of the remaining co-polymers synthesised by the MonomerAddition Procedure is carried out in a similar manner using therespective molar ratios given in the tables.

                                      TABLE 2                                     __________________________________________________________________________    Co-polymerizate in xylene at 80° C., "Batch Method", starter AIBN      added.                                                                                                  Copolymerizate                                      Monomers                  Specific viscosity                                       N containing                                                                            Fatty-alcohol                                                                            10% in xylene,                                                                         Pour-point                                 Example                                                                            olefins                                                                              Mole                                                                             acrylate                                                                              Mole                                                                             25° C.                                                                          [°C.]                               __________________________________________________________________________    1    A      1  behenylacrylate                                                                       1  2.68     -12                                                       (.sup.˜ 70% C.sub.22)                                    2    E      1  behenylacrylate                                                                       1  0.84     -12                                                       (.sup.˜ 70% C.sub.22)                                    3    C      1  behenylacrylate                                                                       1  0.83      -6                                                       (.sup.˜ 70% C.sub.22)                                    4    G      1  behenylacrylate                                                                       1  0.90      -9                                                       (.sup.˜ 70% C.sub.22)                                    5    D      1  behenylacrylate                                                                       1  0.91     -9 to -12                                                 (.sup.˜ 70% C.sub.22)                                    6    H      1  behenylacrylate                                                                       1  0.76     -12                                                       (.sup.˜ 70% C.sub.22)                                    7    B      1  behenylacrylate                                                                       1  1.03      -6                                                       (.sup.˜ 70% C.sub.22)                                    8    I      1  behenylacrylate                                                                       1  1.04      -9                                                       (.sup.˜ 70% C.sub.22)                                    9    F      1  behenylacrylate                                                                       1  1.06     -3 to -6                                                  (.sup.˜ 70% C.sub.22)                                    __________________________________________________________________________

                                      TABLE 3                                     __________________________________________________________________________    Co-polymerizate in xylene at 80° C., "Batch Method", starter AIBN      added.                                                                                                  Copolymerizate                                      Monomers                  Specific viscosity                                       N containing                                                                            Fatty-alcohol                                                                            10% in xylene,                                                                         Pour-point                                 Example                                                                            olefins                                                                              mole                                                                             acrylate                                                                              mole                                                                             25° C.                                                                          [°C.]                               __________________________________________________________________________    10    I     0.1                                                                              Behenylacrylate                                                                       1  1.04     -12 to -15                                                (.sup.˜ 70% C.sub.22)                                    11    K     0.1                                                                              Behenylacrylate                                                                       1  1.03     -15                                                       (.sup.˜ 70% C.sub.22)                                    __________________________________________________________________________

                                      TABLE 4                                     __________________________________________________________________________    Co-polymerization in xylene at 80° C., "Batch Method", starter         AIBN added.                                                                                             Copolymerizate                                      Monomers                  Specific viscosity                                       N containing                                                                            Fatty-alcohol                                                                            10% in xylene,                                                                         Pour-point                                 Example                                                                            olefins                                                                              mole                                                                             acrylate                                                                              mole                                                                             25° C.                                                                          [°C.]                               __________________________________________________________________________    12    L     1  Behenylacrylate                                                                       1  0.62     -3                                                        (.sup.˜ 45% C.sub.22)                                    13    L     1  Behenylacrylate                                                                         0.5                                                                            0.54     +3                                                        (.sup.˜ 45% C.sub.22)                                    14    M       0.1                                                                            Behenylacrylate                                                                       1  1.83     -9 to -12                                                 (.sup.˜ 45% C.sub.22)                                    __________________________________________________________________________

                                      TABLE 5                                     __________________________________________________________________________    Co-polymerizate in xylene at 80° C., "Batch Method", starter AIBN      added.                                                                                                  Copolymerizate                                      Monomers                  Specific viscosity                                       N containing                                                                            Fatty-alcohol                                                                            10% in xylene,                                                                         Pour-point                                 Example                                                                            olefins                                                                              mole                                                                             acrylate                                                                              mole                                                                             25° C.                                                                          [°C.]                               __________________________________________________________________________    15   A      0.1                                                                              Behenylacrylate                                                                       1  2.95      -9                                                       (.sup.˜ 70% C.sub.22)                                    16   A       0.33                                                                            Behenylacrylate                                                                       1  2.23     -12                                                       (.sup.˜ 70% C.sub.22)                                    17   A       0.66                                                                            Behenylacrylate                                                                       1  4.02     -15                                                       (.sup.˜ 70% C.sub.22)                                    18   A      1.0                                                                              Behenylacrylate                                                                       1  2.68     -12                                                       (.sup.˜ 70% C.sub.22)                                    19   A      1.5                                                                              Behenylacrylate                                                                       1  2.62      -6                                                       (.sup.˜ 70% C.sub.22)                                    20   A      3.0                                                                              Behenylacrylate                                                                       1  1.75     +18                                                       (.sup.˜ 70% C.sub.22)                                    __________________________________________________________________________

                                      TABLE 6                                     __________________________________________________________________________    Co-polymerizate in xylene at 80° C.,                                   "Monomer Addition Procedure", starter AIBN added.                                                       Copolymerizate                                      Monomers                  Specific viscosity                                       N containing                                                                            fatty-alcohol                                                                            10% in xylene,                                                                         Pour-point                                 Example                                                                            olefins                                                                              mole                                                                             acrylate                                                                              mole                                                                             25° C.                                                                          [°C.]                               __________________________________________________________________________    21   A      0.1                                                                              Behenylacrylate                                                                       1  1.72     -12                                                       (70% C.sub.22)                                                 22   A       0.33                                                                            Behenylacrylate                                                                       1  1.50     -12                                                       (70% C.sub.22)                                                 23   A       0.66                                                                            Behenylacrylate                                                                       1  1.47     -12                                                       (70% C.sub.22)                                                 24   A      1.0                                                                              Behenylacrylate                                                                       1  1.22      -9                                                       (70% C.sub.22)                                                 25   A      1.5                                                                              Behenylacrylate                                                                       1  1.18      +3                                                       (70% C.sub.22)                                                 26   A      3.0                                                                              Behenylacrylate                                                                       1  1.06     +18                                                       (70% C.sub.22)                                                 __________________________________________________________________________

                                      TABLE 7                                     __________________________________________________________________________    Co-polymerization in xylene, at 80° C., "Batch Method", starter        AIBN added.                                                                                                Copolymerizate                                   Monomers                     Specific viscosity                                    N containing                                                                            fatty-alcohol 10% in xylene,                                                                         Pour-point                              Example                                                                            olefins                                                                              mole                                                                             acrylate   mole                                                                             25° C.                                                                          [°C.]                            __________________________________________________________________________    27   A       0.33                                                                            Behenylacrylate                                                                          1  2.49     -15                                                    (.sup.˜ 45% C.sub.22)                                    28   A       0.66                                                                            Behenylacrylate                                                                          1  2.45     -15                                                    (.sup.˜ 45% C.sub.22)                                    29   A      1.0                                                                              Behenylacrylate                                                                          1  1.84     -12                                                    (.sup.˜ 45% C.sub.22)                                    30   A       0.33                                                                            Behenylacrylate                                                                          1  2.23     -12                                                    (.sup.˜ 70% C.sub.22)                                    31   A       0.66                                                                            Behenylacrylate                                                                          1  4.02     -15                                                    (.sup.˜ 70% C.sub.22)                                    32   A      1.0                                                                              Behenylacrylate                                                                          1  2.68     -12                                                    (.sup.˜ 70% C.sub.22)                                    33   A      1.0                                                                              Behenylacrylate                                                                          1  .sup. 2.21.sup.1                                                                       -3 to -6                                               (.sup. ˜ 70% C.sub.22)                                   34   A      1.0                                                                              Behenylacrylate                                                                          1  .sup. 2.81.sup.2                                                                        -6                                                    (.sup.˜ 70% C.sub.22)                                    35   A      1.0                                                                              Behenylacrylate                                                                          1  .sup. 1.70.sup.3                                                                        +6                                                    (.sup.˜ 70% C.sub.22)                                    36   A      1.0                                                                              Behenylmethacrylate                                                                      1  4.21     +9 to +12                                              (.sup.˜ 70% C.sub.22)                                    37   A      1.0                                                                              Behenylacrylate                                                                          1  2.08      -3                                                    (.sup.˜ 98% C.sub.22)                                    __________________________________________________________________________     .sup.1, 2, 3 Regulator tert. dodecylmercaptan:                                .sup.1 2 · 10.sup.-4 mole/mole double bonds                          .sup.2 1 · 10.sup.-3 mole/mole double bonds                          .sup.3 5 · 10.sup.-3 mole/mole double bonds                     

                                      TABLE 8                                     __________________________________________________________________________    Co-polymerization, variations                                                                 Copolymerization                                              Monomers        Starter AIBN              Copolymerization                    N containing olefin/   Mole/mole                                                                           Additive          Specific Viscosity             fatty alcohol-acrylate double                                                                              temperature                                                                          Method                                                                              Change                                                                             10% in xylene,                                                                         Pour-point            Example                                                                            (1:1 mole) Solvent                                                                              bonds [°C.]                                                                         .sup.4                                                                           .sup.5                                                                           [°C.]                                                                       25° C.                                                                          [°C.]          __________________________________________________________________________    38   A Behenylacrylate                                                                        xylene .sup. 0.014.sup.1                                                                   80     x     88   2.68     -12                        (.sup.˜ 70% C.sub.22)                                              39   A Behenylacrylate                                                                        xylene 0.005 80     x     79   1.34     -9                         (.sup.˜ 70% C.sub.22)                                              40   A Behenylacrylate                                                                        xylene 0.025 80     x     91   2.62     -12 to -15                 (.sup.˜ 70% C.sub.22)                                              41   A Behenylacrylate                                                                        xylene 0.014 100    x     84   1.77     -12 to -15                 (.sup.˜ 70% C.sub.22)                                              42   A Behenylacrylate                                                                        xylene 0.014 80        x  80   1.22     -9                         (.sup.˜ 70% C.sub.22)                                              43   A Behenylacrylate                                                                        xylene 0.014 .sup. 80.sup.2                                                                          x  87   1.54     -12 to -15                 (.sup.˜ 70% C.sub.22)                                              44   A Behenylacrylate                                                                        xylene 0.014 .sup. 90.sup.3                                                                       x     87   1.56     -15                        (.sup.˜ 70% C.sub.22)                                              45   A Behenylacrylate                                                                        tetralin                                                                             0.014 80        x  58   0.70     +6                         (.sup.˜ 70% C.sub.22)                                              46   A Behenylacrylate                                                                        Solvesso 200                                                                         0.014 80        x  84   1.45     -12 to -15                 (.sup.˜ 70% C.sub.22)                                              __________________________________________________________________________     .sup.1 Standard amount                                                        .sup.2 Addition time multiplied by four                                       .sup.3 Addition time multiplied by eight                                      .sup.4 Batch Method                                                           .sup.5 Monomer Addition Procedure                                        

                                      TABLE 9                                     __________________________________________________________________________    Co-polymerization in xylene at 80° C., "Batch Method", starter         AIBN added.                                                                                             Copolymerizate                                      Monomers                  Specific viscosity                                       N containing                                                                            Fatty-alcohol                                                                            10% in xylene,                                                                         Pour-point                                 Example                                                                            olefins                                                                              mole                                                                             acrylate                                                                              mole                                                                             25° C.                                                                          [25° C.]                            __________________________________________________________________________    47   M      1.00                                                                             Behenylacrylate                                                                       1  0.72     +12                                                       (˜45% C.sub.22)                                          48   M      0.66                                                                             Behenylacrylate                                                                       1  0.86      +9                                                       (˜45% C.sub.22)                                          49   M      0.33                                                                             Behenylacrylate                                                                       1  1.04     -12 to -15                                                (˜45% C.sub.22)                                          50   M      0.15                                                                             Behenylacrylate                                                                       1  1.51     -15                                                       (˜45% C.sub.22)                                          51   M      0.15                                                                             Behenylacrylate                                                                       1  .sup. 1.18.sup.1                                                                        -6                                                       (˜45% C.sub.22)                                          52   M      0.15                                                                             Behenylacrylate                                                                       1  1.72     -15                                        53   M      0.15                                                                             Behenylacrylate                                                                       1  .sup. 1.39.sup.1                                                                       -15                                        __________________________________________________________________________     .sup.1 Monomer Addition Procedure                                        

Table 10 contains test results with the compounds of the invention and acomparative product for crude oils important in practice.

                                      TABLE 10                                    __________________________________________________________________________    Tests on crude oils important in practice                                     Co-polymerizate                                                               Example No.                                                                   (Each addition                                                                         Crude oil types with varied pour-points                              400 ppm) PC 16*                                                                            PC 18*                                                                             Dry oil S*                                                                          La Paz**                                                                             La Conception**                                __________________________________________________________________________    18       -3  <-18 <-14  +3       +6                                           50       +3  <-18 <-14  <-20   <-20                                           Comparative                                                                            -3  <-18 <-14  -9     <-20                                           Product                                                                       Without  +18  +15  +15  +3       +9                                           Additive                                                                      __________________________________________________________________________     *Canada                                                                       **Venezuela                                                              

We claim:
 1. A copolymer comprising units of:(1) an acrylate of theformula I

    CH.sub.2 ═CR.sup.1 --CO--OR.sup.2                      (I)

wherein R¹ is hydrogen or methyl, and R² is a linear or branched,saturated or unsaturated aliphatic radical having from 16 to 34 carbonatoms, and (2) N-containing olefins selected from the group consistingof (A) a compound of the formula II

    R.sup.3 --R.sup.4 --O--CO--CR.sup.5 ═CH.sub.2          (II)

wherein R³ is a cyclic imide having of the formula III or IV ##STR7##wherein R⁵ is hydrogen or methyl, R⁶ and R⁷ are together or separatelyhydrogen or C₁ -C₄ -alkyl groups or when taken together are ringfragments of an unsubstituted or a C₁ -C₄ alkyl substituted ring having5 or 6 carbon atoms, R⁴ is (a) a straight-chain or branched alkylenegroup having 1 to 12 carbon atoms optionally sustituted with --OH or--NH₂ group, (b) a straight-chain or branched group having 1 to 12carbon atoms containing the --CH₂ --CH₂ --O--CH₂ --CH₂ - or --CH₂ --CH₂--NH--CH₂ --CH₂ - moiety when the alkylene group contains at least 4carbon atoms, (c) a cyclic C₅ - or C₆ - alkylene group or (d) a C₁ -C₄-alkylene- substituted phenylene group, (B) a compound of formula V

    R.sup.3 --R.sup.8 --CO--OR.sup.9 --O--CO--CR.sup.10 ═CH.sub.2 V

wherein R³ is a cyclic imide having of the formula III or IV ##STR8##wherein R⁶ and R⁷ are together or separately hydrogen or C₁ -C₄ -alkylgroups or when taken together are ring fragments of an unsubstituted ora C₁ -C₄ alkyl substituted ring having 5 or 6 carbon atoms, R⁹ is C₂-C₁₀ alkylene group, R¹⁰ is hydrogen or methyl, R⁸ is a phenyleneradical or an alkylene group of the formula ##STR9## wherein R²⁰ is ahydrogen atom or a branched alkyl radical having from 1 to 11 carbonatoms, and R⁹ is a C₂ -C₁₀ -alkylene group, (C) a compound of formula VI##STR10## wherein R¹⁶ is hydrogen or methyl, R¹² is a phenyl or benzylgroup, R¹³ is a C₁ -C₁₆ -alkyl group and R¹⁶ is a C₂ -C₆ -alkylenegroup, (D) a compound of formula VII

    R.sup.17 --CO--NH--R.sup.18 O--CO--CR.sup.19 ═CH.sub.2 (VII)

wherein R¹⁹ is hydrogen or methyl, R¹⁷ is C₇ -C₃₃ -alkyl group, R¹⁸ is aC₂ -C₄ -alkylene group or combinations thereof in molar ratios of I, toII, V, VI or VII of from about 1:0.1 to about 1:10.
 2. A copolymeraccording to claim 1, wherein R¹ is hydrogen and OR² is a fatty alcoholradical with 16 to 24 carbon atoms.
 3. A copolymer according to claim 1or 2, wherein the compound of formula III is selected from the groupconsisting of phthalimide, methyl-tetrahydro-phthalimide,methyl-hexahydro-phthalimide, maleimide.
 4. A copolymer according toclaims 1 or 2, wherein the compound of formula IV is succinimide.
 5. Acopolymer according to claim 2 wherein R⁴ is a straight- chain orbranched alkylene group with 1 to 6 carbon atoms.
 6. A copolymeraccording to claim 2 wherein R⁸ is a methylene group.
 7. A copolymeraccording to claim 2 wherein R⁸ is a C₁ -C₅ -mono alkyl-substitutedethylene group.
 8. A copolymer according to claim 2 wherein R⁹ of is aC₂ -C₄ -alkylene group.
 9. A copolymer according to claim 2 wherein R¹²is a phenyl or benzyl group, R¹³ is a C₁ -C₄ -alkyl group, and R¹⁴ is aC₂ -C₆ -alkylene group.
 10. A copolymer according to claim 2 wherein R¹²and R¹³ are C₁ -C₄ -alkyl groups and R¹⁴ is a phenylene group.
 11. Acopolymer according to claim 2 wherein R¹⁷ is a C₁₅ -C₂₃ -alkyl group.12. A copolymer according to claim 1 wherein in a compound of formula IR¹ is hydrogen, R² is a linear or branched, saturated or unsaturatedaliphatic radical having from 16 to 24 carbon atoms, and wherein in acompound of formula II R⁶ and R⁷ are together or separately hydrogen orC₁ -C₄ -alkyl groups or when taken together are ring fragments of anunsubstituted or a C₁ -C₄ alkyl substituted ring having 5 or 6 carbonatoms, R⁴ is (a) a straight-chain or branched alkylene group having 2 to8 carbon atoms and wherein R³ is a cyclic imide having of the formulaIII or IV ##STR11## said compounds of formula I and II being present ina molar ratio of from about 1:05 to about 1:2.
 13. A copolymer accordingto claim 11 wherein in a compound of formula II R⁵ is an alkyl radicalhaving from 2 to 3 carbon atoms.
 14. A copolymer according to claim 1wherein in a compound of formula I R¹ is hydrogen, R² is a linear orbranched, saturated or unsaturated aliphatic radical having from 16 to24 carbon atoms, and wherein in a compound of formula VI R¹² is a benzylgroup, R¹³ is a C₁ -C₄ -alkyl group and R¹⁴ is an ethylene group, saidcompounds of formula I and VI being present in a molar ratio of fromabout 1:0 to 1:0.5.
 15. A copolymer according to claim 1 wherein saidring having 5 or 6 carbon atoms is selected from the group consisting ofa cyclopentane ring, a cyclopentene ring, a C₁ -C₄ alkyl substitutedcyclopentane ring, a C₁ -C₄ alkyl substituted cyclopentene ring, abenzene ring, a C₁ -C₄ alkyl substituted benzene ring, a C₁ -C₄ alkylsubstituted 1,4-dihydrobenzene ring, a cyclohexane ring, a C₁ -C₄ alkylsubstituted cyclohexane ring, a cyclohexene ring, a C₁ -C₄ alkylsubstituted cyclohexene ring.